MATLAB: Not enough input arguments error

golden-sectionminimum

Hi everybody ! I have this code as my main function :
function [x,fx,ea,iter]=goldmin(f,xl,xu,es,maxit,varargin)
% goldmin: minimization golden section search
% [x,fx,ea,iter]=goldmin(f,xl,xu,es,maxit,p1,p2,...):
% uses golden section search to find the minimum of f
% input:
% f = name of function
% xl, xu = lower and upper guesses
% es = desired relative error (default = 0.0001%)
% maxit = maximum allowable iterations (default = 50)
% p1,p2,... = additional parameters used by f
% output:
% x = location of minimum
% fx = minimum function value
% ea = approximate relative error (%)
% iter = number of iterations
if nargin<3,error('at least 3 input arguments required'),end
if nargin<4||isempty(es), es=0.0001;end
if nargin<5||isempty(maxit), maxit=50;end
phi=(1+sqrt(5))/2;
iter=0;
fprintf('xl        f(xl)     xu        f(xu)\n')
fprintf('%.3f %9.3f %9.3f %9.3f\n',xl,f(xl,varargin{:}),xu,f(xu,varargin{:}) )
while(1)
    d = (phi-1)*(xu - xl);
    x1 = xl + d;
    x2 = xu - d;
    if f(x1,varargin{:}) < f(x2,varargin{:})
        xopt = x1;
        xl = x2;
    else
        xopt = x2;
        xu = x1;
    end
    iter=iter+1;
    fprintf('%.3f %9.3f %9.3f %9.3f\n',xl,f(xl,varargin{:}),xu,f(xu,varargin{:}) )
    if xopt~=0, ea = (2 - phi) * abs((xu - xl) / xopt) * 100;end
    if ea <= es || iter >= maxit,break,end
end
x=xopt;fx=f(xopt,varargin{:});
and this is the function which i want to find the minimum point :
function y=p3function(x)
y=(1.5.*x.^6-2.*x.^4+12.*x);
each time i call the function i encounter :
>> gm(p3function,-3,3)
Error using p3function (line 2)
Not enough input arguments.
what should i do ?

Best Answer

Two suggestions:
- you used gm instead of goldmin. Are you shure it is wanted that way?
gm(p3function,-3,3)
- Instead of passing a string with the functionname you could try passing a function handle
goldmin(@p3function,-3,3)
This last command worked on my machine
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